UIView+FindController.swift

extension UIViewController {

    /// Traverse up the responder chain until we find a `UINavigationController`.
    func findNavigationController() -> UINavigationController? {
        if let nextResponder = self.next as? UINavigationController {
            return nextResponder
        } else if let nextResponder = self.next as? UIViewController {
            return nextResponder.findNavigationController()
        } else {
            return nil
        }
    }
}

extension UIView {

    /// Traverse up the responder chain until we find a `UINavigationController`.
    func findNavigationController() -> UINavigationController? {
        if let nextResponder = self.next as? UINavigationController {
            return nextResponder
        } else if let nextResponder = self.next as? UIViewController {
            return nextResponder.findNavigationController()
        } else if let nextResponder = self.next as? UIView {
            return nextResponder.findViewController()?.findNavigationController()
        } else {
            return nil
        }
    }

    /// Traverse up the responder chain until we find a `UIViewController`.
    func findViewController() -> UIViewController? {
        if let nextResponder = self.next as? UIViewController {
            return nextResponder
        } else if let nextResponder = self.next as? UIView {
            return nextResponder.findViewController()
        } else {
            return nil
        }
    }
}